Chair type stretching apparatus

ABSTRACT

The chair type stretching apparatus in this invention comprises a seat, a backrest, a flexible sheet, a tension means, and a controller. The backrest has a width. The flexible sheet is disposed in front of the backrest to be movable between a normal position and a projected position. The flexible sheet in the normal position lies in a close relation with a front surface of the backrest. The flexible sheet in the projected position is spaced away from the front surface of the backrest. The tension means is provided on the backrest in order to apply tensional force to the flexible sheet so as to move a center of the flexible sheet toward a front direction of the backrest. The tension means is provided on at least one width end of the backrest in order to apply tensional force along a width direction of the backrest to the flexible sheet.

TECHNICAL FIELD

This invention relates to chair type stretching apparatus having seats and backrests. In particular, this invention relates to a chair type stretching apparatus being configured to stretch user's back and waist.

BACKGROUND ART

Japanese patent application publication No 2002-119558 discloses a prior chair type stretching apparatus. The prior stretching apparatus comprises a seat and a backrest. The stretching apparatus allows the user to stretch the user's back and the user's waist while the user sits on the seat and leans against the backrest. The chair type stretching apparatus further comprises a plurality of air-bags. The air-bags are disposed on the seat and a front surface of the backrest. The air-bags are shaped to expand and contract upon receiving air. The stretching apparatus allows the user to stretch by means of the air-bags.

However, the air-bags of the prior chair type stretching apparatus are configured to support the user, and also are configured to push the user. Therefore, the air-bags of the prior stretching apparatus may not press the user's body according to the user's body size. Consequently, there is a problem that the prior chair type stretching apparatus is difficult to give the stretch to the user.

DISCLOSURE OF THE INVENTION

This invention is achieved to solve the above problem. An object in this invention is to give the stretch to the user certainly.

In order to solve the above problem, the chair type stretching apparatus in this invention has a seat and a backrest. The seat and the backrest have individual widths along a width of a user's body. The chair type stretching apparatus comprises a flexible sheet, a tension means, and a controller. The flexible sheet is disposed in front of the backrest and extends an entire width of the backrest for supporting the user's body. The flexible sheet is configured to be movable between a normal position and a projected position. The flexible sheet in the normal position lies in a close relation with a front surface of the backrest. The flexible sheet in the projected position is spaced away from the front surface of the backrest. The tension means is provided on the backrest. The tension means is configured to apply tensional force to the flexible sheet so as to move a center of the flexible sheet toward a front direction of the backrest. The controller is configured to control the tension means in order to move the center of the flexible sheet to a front-back direction. The tension means is provided on at least one width end of the backrest in order to apply the tensional force along a width direction of the backrest to the flexible sheet. Consequently, the tension means moves the center of the flexible sheet to the front-back direction.

The chair type stretching apparatus with this configuration is configured to move a a predetermined portion such as a user's back and a user's lower back by means of the flexible sheet. Therefore, this configuration makes it possible to give the stretch to the user regardless of the user's body size. In addition, the tension means being disposed at least one width end of the front surface of the backrest. Therefore, the chair type stretching apparatus with this configuration achieves reduction of the cost and downsizing of the dimension.

It is preferred that the tension means is realized by pressurizing means. The pressurizing means are configured to apply force toward the front direction of the backrest to the flexible sheet. The pressurizing means is located between the backrest and the flexible sheet such that the pressurizing means moves the center of the flexible sheet toward the front direction. The controller being configured to control the pressurizing means so as to move the center of the flexible sheet along the front-back direction of the backrest. The pressurizing means are respectively disposed to both width ends of the backrest in order to apply the force toward a front direction of the backrest to the flexible sheet. Consequently, the pressurizing means moves the center of the flexible sheet toward a front direction of the backrest.

In this case, the chair type stretching apparatus is capable of moving the predetermined portion such as the user's back and the user's lower back by means of the flexible sheet. Therefore, the chair type stretching apparatus with this configuration is capable of giving the stretch to the user surely regardless of the user's body size.

It is preferred that the pressurizing means is composed of air-bags and a pump. The air-bags are configured to expand and contract along the front-back direction. The pump is configured to send air to the air-bags.

In this case, when the chair type stretching apparatus is deactivated, the air-bags are contracted. Therefore, the chair type stretching apparatus with this configuration achieves the downsizing of the dimension.

It is preferred that the flexible sheet and the pressurizing means are detachably attached to the backrest.

In this case, it is possible to vary the position of the flexible sheet and the pressurizing means within the front surface of the backrest. Therefore, this configuration makes it possible for the chair type to vary the portion of giving the stretch to the user.

It is preferred that the chair type stretching apparatus further comprises a stretching unit. The stretching unit is detachably attached to the front surface of the backrest. The stretching unit is provided at its front surface with the flexible sheet. The stretching unit is provided at its both width ends of an inside of the stretching unit with the pressurizing means. Consequently, the flexible sheet and the pressurizing means are detachably attached to the backrest.

In this case, this configuration makes it possible to vary the position of the flexible sheet and the pressurizing means on the front surface of the backrest. Therefore, with this configuration, it is possible to obtain the chair type stretching apparatus being configured to give the stretch to various portion of the user.

It is preferred that the both width ends of the flexible sheet are respectively attached to the both width surfaces of the backrest. In addition, it is preferred that the flexible sheet has at least one the width ends which is attached to a predetermined area of the width surface of the backrest.

In this case, it is possible to vary an amount of the slack along the width direction of the flexible sheet. Consequently, this configuration makes it possible to obtain the chair type stretching apparatus which is configured to apply stretch at a predetermined intensity which is varied by adjusting an amount of the slack.

It is preferred that the chair type stretching apparatus further comprises a wall. The wall is located between the backrest and the flexible sheet. The wall is located at one width end of the front surface of the backrest. Tension means is defined by a pressurizing means. The pressurizing means is configured to apply force along the front direction of the backrest to the flexible sheet. The tension means is located between the backrest and the flexible sheet so as to move the center of the flexible sheet. The controller is configured to control the pressurizing means in order to move the center of the flexible sheet toward the front-back direction. The pressurizing means is located at one width end of the backrest. The pressurizing means is located away from the wall. The pressurizing means is configured to apply the force along the front direction of the backrest to one end of the flexible sheet so that the pressurizing means applies the tensional force directed outwardly of the width direction to the flexible sheet.

In this case, the flexible sheet also moves the portion of the user such as the shoulder, the back, and the lower back. Therefore, this configuration also makes it possible to give the stretch to the user regardless of the user's body size.

It is also preferred that the chair type stretching apparatus further comprises walls. The walls are provided on the front side of the backrest. The walls are respectively located at both width ends of the front surface of the backrest. The tension means is defined by rollers. The rollers respectively hold the width ends of the flexible sheet. The rollers are configured to wrap the flexible sheet around the rollers so as to move the center of the flexible sheet toward the front direction of the backrest. The controller is configured to control the rollers in order to move the center of the flexible sheet to the front-back direction. The rollers are respectively disposed at both width surfaces of the backrest for wrapping the flexible sheet, whereby the roller applies the tension directed outwardly of the width direction to the flexible sheet.

In this case, the flexible sheet also moves the portion of the user such as the shoulder, the back, and the lower back. Therefore, this configuration also makes it possible to give the stretch to the user regardless of the user's body size.

It is preferred that the backrest is formed at its center of the front surface with an opening. The backrest has an applicator. The applicator is disposed within the backrest. The applicator is configured to move toward a front direction from the opening to apply force along the front direction. The flexible sheet is shaped to cover the opening.

In this case, it is possible to obtain the chair type stretching apparatus which is configured to give a massage to the user. In addition, the applicator is moved toward a front direction even the flexible sheet is located in front of the applicator by slacking the flexible sheet. Therefore, it is possible to obtain the chair type stretching apparatus being configured to give the massage to the user by the applicator.

It is preferred that the flexible sheet is composed of a front cover and a rear cover. The front cover is located in front of the rear cover. The rear cover lies in a close relation with the front surface of the backrest. The rear cover has an expansion ratio or an amount of slack along the width direction. The expansion ratio of the rear cover is smaller than the expansion ratio of the front cover. Or, an amount of the slack of the rear cover is smaller than an amount of the slack of the front cover.

In this case, it is possible to obtain the chair type stretching apparatus having the flexible sheet which is mild to skin, and is capable of keeping good looking.

It is preferred that the flexible sheet has an expansion ratio along a height direction of the backrest, and an expansion ratio along the width direction of the backrest. The expansion ratio along the width direction is smaller than the expansion ratio along the height direction.

In this case, when the chair type stretching apparatus gives the stretch to the user, the tension means is capable of applying the tensional force along the width direction to the flexible sheet immediately. In addition, when the chair type stretching apparatus gives the massage to the user, the applicator is easily moved along the vertical direction.

It is preferred that the flexible sheet has an amount of slack along a height direction, and an amount of slack along the width direction. An amount of the slack along the width direction is smaller than an amount of the slack along the height direction.

In this case, when the chair type stretching apparatus gives the stretch to the user, the tension means is also capable of applying the tensional force along the width direction to the flexible sheet immediately. In addition, when the chair type stretching apparatus gives the massage to the user, the applicator is also easily moved along the vertical direction.

It is preferred that the flexible sheet has a first area and a second area. The first area receives the tensional force along the width direction from the pressurizing means. The second area receives the force along the front direction from the applicator. The first area has an expansion ratio or an amount of slack. The second area has an expansion ratio or an amount of slack. The expansion ratio of the first area is smaller than the expansion ratio of the second area. An amount of the slack of the first area is smaller than an amount of the slack of the second area.

In this case, it is possible to obtain the chair type stretching apparatus which is configured to give the stretch to the user optimally, and also is configured to give the massage to the user optimally.

Further characteristics of the present invention and effects resulting there from can be better understood based on the best mode for carrying out the invention and examples thereof described below.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 (a) shows a perspective view of the chair type stretching apparatus in the first embodiment.

FIG. 1 (b) shows a perspective view the chair type stretching apparatus of the first embodiment without flexible sheets, pressurizing means, and the applicator cover.

FIG. 2 (a) shows a side view of the backrest having a normal condition.

FIG. 2 (b) shows a side view of the backrest having a reclining condition.

FIG. 3 (a) shows a side view of the seat when the air-bag on the seat is expanded.

FIG. 3 (b) shows a side view of the backrest when the air-bag on the backrest is expanded.

FIG. 4 (a) shows a perspective view of the chair type stretching apparatus of a first modification in the first embodiment. The air-bags on the left side of the backrest and the left side of the seat are expanded.

FIG. 4 (b) shows a perspective view of the chair type stretching apparatus of the first modification in the first embodiment. The air-bags on the left side of the backrest and the right side of the seat are expanded.

FIG. 5 (a) shows a top view of the backrest with the air-bags which is contracted.

FIG. 5 (b) shows a top view of the backrest with the air-bags which is expanded.

FIG. 5 (c) shows a top view of the backrest with the air-bag on only the left side of the backrest is expanded.

FIG. 6 shows a front view of the backrest.

FIG. 7 (a) shows a front schematic view of the chair type stretching apparatus with the air-bags disposed on both lateral end of the seat. Both the air-bags are contracted.

FIG. 7 (b) shows a front schematic view of the chair type stretching apparatus with the air bags disposed on both lateral end of the seat. Both the air-bags are expanded.

FIG. 8 shows a schematic view of a relationship of a controller, a pump, electromagnetic valves, and air-bags.

FIG. 9 (a) shows a perspective view of the chair type stretching apparatus of a second modification in the first embodiment. This stretching apparatus is provided at its front surface of the backrest with a stretching unit.

FIG. 9 (b) shows a schematic side cross sectional view of the stretching unit.

FIG. 10 shows a perspective view of the backrest of the chair type stretching apparatus of a third modification of the first embodiment. The flexible sheet is attached to the backrest.

FIG. 11 (a) shows a perspective view of the chair type stretching apparatus in the fourth modification.

FIG. 11 (b) shows a top cross sectional view of the backrest in the fourth modification.

FIG. 12 shows a perspective view of the backrest in the fourth modification. This figure shows positions of the air-bags on the backrest.

FIG. 13 (a) shows a top view of the chair type stretching apparatus in the fifth modification while the air-bags are contracted.

FIG. 13 (b) shows a top view of the chair type stretching apparatus in the fifth modification while the air-bags are expanded.

FIG. 14 (a) shows a top cross sectional view of the chair type stretching apparatus in the sixth modification. In this figure, the flexible sheet is slacked.

FIG. 14 (b) shows a top cross sectional view of the chair type stretching apparatus in the sixth modification. In this figure, the flexible sheet is wrapped by the rollers.

FIG. 15 shows a front view of the chair type stretching apparatus in a seventh modification.

FIG. 16 shows a front cross sectional view of the seat of the chair type stretching apparatus in the eighth modification.

FIG. 17 (a) shows a front cross sectional view of the air-bag which is contracted.

FIG. 17 (b) shows a front cross sectional view of the air-bag which is expanded.

FIG. 18 (a) shows a top cross sectional view of the flexible sheet of the chair type stretching apparatus in a tenth modification. In this figure, the flexible sheet is slacked.

FIG. 18 (b) shows a top cross sectional view of the flexible sheet of the chair type stretching apparatus in the tenth modification. In this figure, the flexible sheet is wrapped by the roller.

FIGS. 19 (a) and (b) shows a side cross sectional view of the backrest of the chair type stretching apparatus of the above.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

The chair type stretching apparatus in this embodiment is explained with attached drawings. In FIG. 1, a front direction of the chair type stretching apparatus is indicated by means of an arrow of X. Similarly, a left direction of the chair type stretching apparatus is indicated by means of an arrow of Y. An upper direction of the chair type stretching apparatus is indicated by means of an arrow of Z. In FIG. 1, a lateral direction of the chair type stretching apparatus is equivalent to a width direction of the chair type stretching apparatus. A height direction of the chair type stretching apparatus is equivalent to a vertical direction of the chair type stretching apparatus. The front-back direction of the chair type stretching apparatus is equivalent to a depth direction of the chair type stretching apparatus.

FIG. 1 (a) shows a perspective view of the chair type stretching apparatus 100 of the first embodiment in this invention. The chair type stretching apparatus in this embodiment 100 comprises a base 200, a seat 300, a backrest 400, arm rests 900, and a foot rest 901. The base is shaped to support the seat 300, the backrest 400, the arm rests 900, and the foot rest 901. The base 200 has a front surface which supports the foot rest 901. The base 200 has a top surface which supports the seat 300. The base 200 has a rear surface which supports the backrest 400 which extends toward the upper direction. The base 200 has both width ends which respectively hold the arm rests 900. The base is provided at its inside with a pump 200 and a controller 240. The pump 220 and the controller 240 are activated upon receiving the electrical power. In addition, the chair type stretching apparatus 100 further comprises a reclining mechanism (which is not shown) for reclining the backrest 400. In addition, the chair type stretching apparatus 100 further comprises an operation setting device (which is not shown). The operation setting device is provided for setting the operation of the pump. The pump 220 is activated upon receiving the electrical power.

The backrest 400 has a width along a lateral direction. In other words, the backrest 400 has the width along a width of the body of the user. As shown in FIG. 1 (a), the backrest 400 includes an applicator cover 410, an air-bag 420, an air bag 430, a flexible sheet 421, and a flexible sheet 431. FIG. 1 (b) shows the chair type stretching apparatus 1 without the applicator cover 410, the flexible sheet 421, the flexible sheet 431, the air-bag 420, and the air-bag 430. As shown in FIG. 1 (b), the backrest 400 is formed at its front surface with an opening 440. The opening 440 extends along a height direction of the backrest 400.

The backrest 400 includes applicators 441, arms 442, and a massaging device 443. The applicator 441, the arms 442, and the massaging device 443 are disposed within the opening 440. The arms 442 have front ends which respectively hold the applicators 441. The massaging device 443 holds rear ends of the arms 442. The arms 442 hold the applicators to be movable toward a front direction of the backrest 400. The massaging device 443 is activated upon receiving the electrical power. In addition, FIG. 2 (a) shows a side cross sectional view of the chair type stretching apparatus 100. As shown in FIG. 2 (a), the backrest 400 includes a guide rail 444. The guide rail 444 is provided for sliding the massaging device 443 along the guide rail 444. The guide rail 44 4 is disposed within the backrest 400 and extends along a vertical direction. Consequently, the massaging device 443 moves along the height direction within the opening 440. Each of the flexible sheet 421 and the flexible sheet 431 has slack. The flexible sheets 421 and 431 are provided on the backrest 400 to extend an entire width of the backrest 400. Consequently, the flexible sheets 421 and 431 cover the opening 440 in order to conceal the massaging device 443, the arms 442, and the applicators 441. The applicators 441 are configured to apply force to the applicator cover 410. The force generated by the applicators 441 is directed toward a front direction. Consequently, the applicators 441 applies the force which is directed toward a front direction to the applicator cover 410. Therefore, the applicators 441 generates the force which is transmitted to the user's body through the applicators cover 410, thereby giving the massage to the user.

The air-bags 420 are respectively disposed on the front surface of the backrest 400 and respectively located at both width ends of the backrest 400. The air-bags 430 are respectively disposed on the front surface of the backrest 400 and respectively located at both width ends of the backrest. The air-bag 420 and the air-bag 430 are arranged along a height direction of the backrest. The air-bag 420 and 430 are respectively shaped to have bellows shown in FIG. 4. The air-bags 420 and 430 have bottom surfaces which are respectively attached to the front surface of the backrest 40 by snap pins. The air bags 420 and 430 are connected to the pump 220 and the electromagnetic valves through the hoses 230 respectively, shown in FIG. 8. The pump 220 is configured to send the air to the air-bags 420 and 430. The air-bags 420 and 430 are configured to expand when the air is sent from the pump 220. Because the air-bags 420 and 430 are arranged on the front surface of the backrest 440, the air-bags 420 and 430 expand toward the front direction of the backrest upon receiving the air. On the other hand, the air-bags 420 and 430 are contracted toward the backrest when the air in the air-bags 420 and 430 is released.

Each one of the flexible sheets 421 and 431 is made of a cloth. The flexible sheets 421 and 431 are disposed in normal positions of lying in a close relation with a front surface of the backrest. The flexible sheets 421 and 431 are located in front of the air-bags 420, 430. The flexible sheets 421 and 431 are provided on the backrest 400 so as to extend over an entire width of the backrest 400. The flexible sheets 421 and 431 respectively have both width ends. Both width ends of the flexible sheets 421 and 431 are sewed on a width side surface of the backrest 400. The air-bags 420 and 430 are respectively provided at its front surface with loop tapes. On the other hand, the flexible sheets 421 and 431 are respectively provided at its rear surface with hook tapes. Consequently, the air-bags 420 have the front surfaces which are fastened to the rear surface of the flexible sheet 420 by means of hook-and-loop fastener. Similarly, the air-bags 430 have the front surfaces which are fastened to the rear surface of the flexible sheet 431 by means of hook-and-loop fastener. The flexible sheet 421 has its width center which is faced to a lower back of the user in order to support the user's lower back. The flexible sheet 431 has its width center which is faced to the back of the user in order to support the user's back.

FIG. 6 shows a front view of the above chair type stretching apparatus. FIG. 7 shows a front cross sectional view of the above chair type stretching apparatus. As shown in FIG. 6, the seat 300 has a depth along the front-back direction, and a width along a width of a body of a user who seats on the seat 300. As shown in FIG. 1 (a) and FIG. 6, the seat 300 includes air-bags 310 and a flexible sheet 311.

The air-bags 310 are disposed on both width ends of the top surface of the seat 300. The air-bags 310 are respectively shaped to have bellows shown in FIG. 4. Each air-bag 310 is connected to the pump 220 through an electromagnetic valve 210 and a hose 230. The air-bag 310 has its bottom surface which is attached to the top surface of the seat 300 by means of the snap pin. The air-bag 310 is configured to expand and contract upon receiving the air from the pump 220. Therefore, the air-bags 310 disposed on the top surface of the seat 300 are expanded toward an upper direction of the seat 300 upon the air is sent to the air-bags 310. On the other hand, the air-bags 310 disposed on the top surface of the seat 300 are contracted toward a lower direction of the seat 300 when the air is removed from the air-bags 310.

The flexible sheet 311 is made of the cloth. The flexible sheet 310 is disposed on the top surfaces of the seat 300 and the air-bags 310. The flexible sheet 310 extends over an entire width of the seat 300. The flexible sheet 311 has its width center which is faced with the buttocks. The air-bags 310 are respectively provided at its top surfaces with loop tapes which are not shown. On the other hand, the flexible sheet 311 is provided at its rear surface which is faced with the top surface of the air-bags 310. The rear surface of the flexible sheet 311 is provided with hook tapes which are not shown. Consequently, the top surface of the air-bag 310 is fastened to the rear surface of the flexible sheet 311 by means of the hook-and-loop fastener. The flexible sheet 311 has both lateral ends which are respectively sewed to the both width surface of the seat 300. It is noted that the flexible sheet 311 is preferably made of a hard foamed material. The hard foamed material is exemplified by the urethane.

FIG. 8 shows a controller 240 being configured to control the air-bags 420, 430, 310, the electromagnetic valves 210, and the pump 220. The controller 240 includes a pump control circuit 241 and the valve control circuit 242. The controller 240 sends a control signal on the basis of setting of an operation device operated by the user. When the valve control circuit 241 receives the control signal, the valve control circuit 242 opens and closes the electromagnetic valves 210 on the basis of the control signal. In addition, when the pump control circuit 241 receives the control signal, the pump control circuit 241 controls the pump 220 to start or stop. Consequently, the pump 220 sends the air to the air-bag 420, 430, and 310 through the hoses 230. Furthermore, the controller 240 controls the valve control circuit 242 and the pump control circuit 241 respectively in order to expand and contract the air-bags 420, 430, 310.

The chair type stretching apparatus 100 operates as follows. When the setting is entered by the operation device, the controller 340 controls the pump 220 and the electromagnetic valves 210 in order to send the air to the air-bags 420 and 430. Because the air-bags 420 and 430 are disposed on the front surface of the backrest 400, the air-bags 420 and 430 expands along the front direction of the backrest. Consequently, the air-bags 420 and 430 apply the force along the front direction of the backrest to the both width ends of the flexible sheets 421 and 431. That is, the air-bags 420 and 430 act as pressurizing means being configured to apply force toward the front direction of the backrest to the flexible sheets 421 and 431. Both the lateral ends of the flexible sheets 421 and 431 are sewed to the both width surfaces of the backrest 400. Therefore, the air-bags 420, 430 generate the tensional force along outwardly of the width direction of the flexible sheet according to the expansion of the air-bags 420 and 430. That is, the air-bags 420 and 430 acts as the tension means which is configured to generate the tensional force which are along the flexible sheets 421 and 431 which are applied to the flexible sheets 421 and 431. When the air-bags 420 and 430 applies the tensional force along the lateral direction of the flexible sheet 421, 431, the air-bags 420 and 430 moves the lateral center of the flexible sheets 421 and 431 to front-back directions.

In addition, on the basis of the setting of the operation device, the controller 240 controls the pump 220 and the electromagnetic valves 210, whereby the pump 220 sends the air to the air-bag 310. The air-bags 310 are disposed on the top surface of the seat 300. Therefore, the air-bags 310 expand toward the upper direction of the seat 300. Consequently, the air-bags 310 apply the force toward the upper direction of the seat 300 to both the width ends of the flexible sheet 310 on the seat 300. That is, the air-bags 310 act as the pressurizing means for applying the force toward the upper direction of the seat 311. Both the width ends of the flexible sheet 311 are sewed to both the lateral surface of the seat 300. Therefore, when the air-bags 310 are expanded, the air-bags 310 generate the tensional force along outwardly the width direction of the flexible sheet 311. That is, the air-bags 310 act as the tension means being configured to generate the tensional force which is along the width direction of the seat and which is applied to the flexible sheet 310. The air-bags 310 move the width center of the flexible sheet 311 toward the upper direction by applying the tensional force along the lateral direction of the flexible sheet 311 to the flexible sheet 311.

The chair type stretching device 100 with this configuration makes it possible to give the stretch to the user who sits on the seat and leans against the backrest. FIG. 3 (b) shows the chair type stretching device 100 which moves the user's lower back by controlling the air-bags 430 which is disposed on the position corresponding to the user's lower back. In addition, FIG. 3 (a) shows the chair type stretching device 100 which moves the user's buttock by controlling the air-bags 310 which is disposed on the position corresponding to the user's buttocks.

FIG. 4 shows a chair type stretching apparatus 100 of a first modification of the first embodiment. In this modification, the backrest 400 includes the air-bags 420 (composed of 420L and 420R), and the flexible sheet 421. The air-bags 420L and 420R are disposed on backrest 400 to be located at a position corresponding to the user's back. The flexible sheet 421 is disposed on the backrest 400 to be located at a position being faced to the user's back. The seat 300 includes the air-bags 310 (composed of 310L and 310R) and the flexible sheet 311. As shown in FIG. 4 (a), the air-bag 420L and 310L are respectively disposed on the left side of the backrest 400 and the left side of the seat 300. The pump 220 sends the air to the air-bag 420L and 310L. Consequently, the flexible sheets 421 and 311 respectively have left ends which are spaced away from the backrest 400 and the seat 300, thereby the flexible sheet 421 and 311 are located in the projected positions with respect to the backrest 400 and the seat 300. Therefore, the chair type stretching apparatus 100 gives the stretch of turning of the user to the right about an axis along a height of the user.

In addition, as shown in FIG. 4 (b), the pump 220 sends the air to the air-bag 421L disposed on the left side of the backrest 400. On the other hand, the pump 220 sends the air to the air-bag 310R disposed on the right side of the backrest 400. Consequently, the flexible sheet 421 has its left end being located in the front position. Therefore, the flexible sheet 421 and 311 give the stretch to the user sitting on the chair type stretching apparatus. In particular, the chair type stretching apparatus turns the user's upper body to the right about the axis along the height of the user by means of the flexible sheet 421. On the other hand, the chair type stretching apparatus turns the user's lower body to the left about the axis along the height of the user by means of the flexible sheet 311. Consequently, this configuration makes it possible for the chair type stretching apparatus to give the stretch of twisting an upper body of the user with respect to the lower body.

FIG. 5 shows a top view of the first embodiment and the first modification of the chair type stretching apparatus. FIG. 5 shows the condition of the user's upper body with respect to the chair type stretching apparatus. As shown in FIG. 5 (b), the chair type stretching apparatus with the above configuration is configured to move the user's upper body toward the projected position regardless of the width of the body of the user. In addition, the configurations of the seat 300, the flexible sheet 311, and the air-bags 310 makes it possible for the chair type stretching apparatus to move the user's buttocks toward the upper direction regardless of the width of the body of the user. In addition, as shown in FIG. 5 (c), the chair type stretching apparatus with this configuration turns the user's body to the right regardless of the width of the body of the user.

FIG. 9 shows a chair type stretching apparatus of a second modification of the first embodiment. In this modification, the chair type stretching apparatus comprises a stretching unit 450. The stretching unit 450 is provided at its one surface with a flexible sheet 422. The stretching unit 450 is shaped to have a sack. The air-bags 420 and 430 are disposed within the stretching unit 450. Consequently, both the air-bags 420 are disposed in the both lateral ends of an inside of the stretching unit 450. Similarly, both the air-bags 430 are disposed in the both lateral ends of the inside of the stretching unit 450.

The stretching unit 450 of this modification is shaped to cover an entire front surface of the backrest 400. The stretching unit 450 is provided at its upper end with the fastener 451. Consequently, the stretching unit 450 is disposed on the backrest 400 by means of the fastener 451. That is, the stretching unit 450 is detachably attached to the backrest 400. Therefore, the flexible sheet 422, and the air-bags 420, 430 are detachably attached to the backrest 400. The stretching unit 450 includes a hose 230 which is communicated with the air-bags 420, 430. The hose 230 is pulled outwardly from the width surface of the stretching unit 450. The hose 230 has its one end with a connecting port (not shown) which is connected to the pump 220. The pump 220 is configured to send the air to the air-bags 420 and 430 through the hose 230.

Therefore, when the stretching unit 450 having the flexible sheet 422 is disposed in a close relation to a front surface of the backrest 400, the air-bags 420, 430 are respectively configured to apply tensional force along the lateral direction to the flexible sheet according to the expansion of the air-bags 420, 430. Consequently, it is possible to obtain the chair type stretching apparatus being configured to give the stretch to the user. It is noted that the stretching unit 450 preferably has a plurality of fasteners 451. Each the fastener 451 extends along the lateral direction to form a plurality of lines. In this case, it is possible to select the one of the lines of the fasteners for attaching the stretching unit 450 to the backrest 400. Consequently, the vertical position of the stretching unit 450 is varied. In addition, it is also possible to detach the stretching unit 450 from the backrest 400. Consequently, the chair type stretching apparatus is configured to give a massage to the user by means of the applicators.

FIG. 10 shows a backrest 400 of a chair type stretching apparatus of a third modification of the first embodiment. In this modification, the flexible sheet 421 is provided at its both lateral ends of the rear surface with the hook tapes 460. The backrest 400 is provided at its both lateral surfaces with certain areas holding the loop tapes 461. Consequently, the flexible sheet 421 is configured to be attachable to both the lateral surface of the backrest 400.

Therefore, the chair type stretching apparatus is configured to give the stretch to the user when the flexible sheet 421 is disposed on the backrest 400 and the air-bags 420 are extended. In addition, the loop tapes 461 are disposed on the certain areas of the both lateral surface of the backrest 400. Therefore, the flexible sheet 421 has both lateral ends which are respectively detachably attached to the certain areas of the both lateral surfaces of the backrest 400. Consequently, it is possible to vary slack in the lateral direction of the flexible sheet 421. As a result, it is possible to adjust intensity of the stretch which is given to the user. In addition, the flexible sheet is movable along a vertical direction. Therefore, it is possible to adjust the position for giving the stretch to the user. It is noted that it is only required for the flexible sheet 421 to have one lateral end which is detachably attached to the backrest 400.

FIG. 11 shows a fourth modification of the first embodiment of the chair type stretching apparatus. In this modification, the flexible sheet 422 further plays a role of an applicator cover for covering the applicators.

The flexible sheet 422 is provided with an outer cover 471 and the inner cover 470. The outer cover 471 is configured to come into directly contact with the user's body. That is, the outer cover 471 is equivalent to a front cover. The inner cover 470 is configured to come into directly contact with the front surface of the backrest 400. That is, the inner cover 470 is equivalent to a rear cover. The outer cover 471 has an amount of slack or an extension ratio along the lateral direction of the outer cover 471 which is larger than an amount of the slack or the extension ratio along the lateral direction of the inner cover 470. FIG. 11 (b) shows a top cross sectional view of the backrest in this modification. As shown in FIG. 11 (b), the flexible sheet 422 has both lateral ends which are respectively attached to both the lateral surface 400L 400R of the backrest 400. Consequently, the flexible sheet 422 covers the opening 440 of the backrest 400.

Therefore, the chair type stretching apparatus with this configuration is configured to give the stretch to the user, and also to give the massage to the user.

In this modification, the flexible sheet 422 has the inner cover 470 and the outer cover 471. The inner cover 470 has an amount of the slack or the extension ratio which is smaller than an amount of the slack or the extension ratio of the outer cover 471. In this modification, the flexible sheet 422 has the inner cover 470 and the outer cover 471. The inner cover 470 has an amount of the slack or the extension ratio in the width direction which is smaller than an amount of the slack or the extension ratio in the width direction of the outer cover 471.

With this configuration, the inner cover 470 is capable of generating the tensional force along the width direction when the air-bags 470 apply the force toward the front direction to the inner cover 470. In addition, the outer cover 471 with this configuration is mild to skin, and is capable of keeping good looking.

In this modification, the inner cover 470 has the extension ratio along the vertical direction which is smaller than the extension ratio along the lateral direction of the inner cover 470. Therefore, this configuration makes it possible for the air-bag 420 to generate the tensional force along the width direction of the flexible sheet when the chair type stretching apparatus gives the stretch to the user. In addition, this configuration makes it possible for the applicators 441 move along the vertical direction while the applicators 441 extends the flexible sheet along the vertical direction. Consequently, the applicator 441 is capable of giving the massage to the user through the flexible sheet 422.

Further, it is also preferred that the flexible sheet 422 is sewed to the backrest such that the flexible sheet 422 has an amount of the slack along the lateral direction which is smaller than an amount of the slack along the vertical direction of the flexible sheet 422. This configuration makes it possible for the air-bags 420 to generate the tensional force along the width direction of the flexible sheet 422 effectively when the chair type stretching apparatus gives the stretch to the user. In addition, this configuration also makes it possible for the applicators 441 to give the massage to the user while the applicators 441 extend the flexible sheet along the vertical direction. Consequently, the applicator 441 is capable of giving the massage to the user through the flexible sheet 422.

Moreover, it is also preferred that the flexible is configured to generate the tensional force along the lateral direction which differs according to portion. As shown in FIG. 12, the flexible sheet has a first portion S1 and a second portion S2. The first portion S1 extends along an entire width of the backrest. The first portion S1 of the flexible sheet is given the tensional force along the lateral direction by the air-bags. The second portion S2 extends along an entire width of the backrest. The second portion S2 is given the force toward a front direction by the applicators 441. The first portion S1 is configured to extend at a first extension ratio along the width direction. The second portion S2 is configured to extend at a second extension ratio along the width direction. The second extension ratio is larger than the first extension ratio. Such a flexible sheet 422 is obtained by sewing the flexible sheet having the first extension ratio to the flexible sheet having the second extension ratio such that the flexible sheet having the second extension ratio is located in an upper side of the flexible sheet having the first extension ratio. Moreover, it is also possible to obtain the flexible sheet 422 having the extension ratio which gradually becomes smaller from the upper end toward the lower end.

Consequently, the flexible sheet is capable of having a predetermined portion where the tensional force is easily generated. Therefore, when the flexible sheet is disposed such that the flexible sheet is faced to a portion of the user to be stretched, the flexible sheet is capable of giving the stretch to the user effectively. In addition, it is also possible for the predetermined portion to have flexibility. Consequently, it is possible to give the massage to the user effectively. Therefore, it is possible to obtain the flexible sheet having two effects.

On the other hand, it is also preferred that the first portion S1 has an amount of the slack along the lateral direction which is different from an amount of the slack along the lateral direction of the second portion S2. In this case, the flexible sheet 422 has the first portion S1 extends along the width direction, and the second portion S2 extends along the width direction. The first portion S1 is shaped to have a first length along the width direction. The second portion S2 is shaped to have a second length along the width direction. The second length is larger than the first length. That is, the second portion S2 has an amount of the slack which is greater than an amount of the slack of the first portion S1. With this configuration, it is possible for the flexible sheet to have the predetermined portion which is easily given the tensional force and which is faced to the back and lower back of the user to be stretched. Consequently, it is possible to give the stretch to the user effectively. In addition, the portion of the flexible sheet faced to the user's shoulder is capable of having flexibility. Therefore, the applicators are capable of giving the massage to the user. As a result, it is possible to obtain the flexible sheet having the two effects. Such the flexible sheet is obtained by sewing the flexible sheet having the first length along the width direction to the flexible sheet having the second length along the width direction such that the flexible sheet having the second length is located in an upper side of the flexible sheet having the first length. Moreover, it is also possible to obtain the flexible sheet 422 having the length along the width direction which gradually becomes smaller from the upper end toward the lower end.

FIG. 13 shows a fifth modification of the first embodiment of the chair type stretching apparatus. In this modification, the backrest is provided at its left end of the front surface with a wall 480 instead of the air-bag. The backrest is provided at its right end of the front surface with the air-bag 420. The flexible sheet 421 is located in front of the wall 480 and the air-bag 420. The left end of the flexible sheet 421 is fixed to a front end of the wall 480. The right end of the flexible sheet is fixed to the right side surface 400R of the backrest 400. When the air-bag 420 is expanded, the front end of the air-bag 420 is moved to a position in the front-back direction. As a result, the front end of the air-bag 420 is located at a level same as the level of the front end of the wall 480.

With this configuration, as shown in FIG. 13 (b), when the air-bag 420 is expanded, the air-bag 420 applies the tensional force along the lateral direction of the flexible sheet 421 to the flexible sheet 421. When the tensional force is applied to the flexible sheet, the width center of the flexible sheet 421 is moved toward to front direction. As a result, the flexible sheet 421 moves a portion of the user corresponding to the lateral center of the flexible sheet 421. As a result, the chair type stretching apparatus gives the stretch to the user. In addition, when the air-bag 420 is contracted as shown in FIG. 13 (a), the flexible sheet 421 has a slack condition. As a result, the user's back is moved toward a position along the backrest 400. Therefore, chair type stretching apparatus is capable of giving the massage to the user by the applicators within the opening 440. It is noted that backrest 400 in this modification is provided at its left end with the wall 480, and is provided at its right end with the air-bag 420. However, it is possible to employ the backrest 400 which is provided at its right end with the wall, and is provided at its left end with the air-bag.

FIG. 14 shows a sixth modification of the embodiment of the chair type stretching apparatus. In this modification, the backrest 400 has the walls 480 and rollers 490 instead of the air-bags. That is, the backrest 400 is provided at its both lateral end of the front surface with the walls 480. Both the walls extend toward the front direction of the backrest 400. The rollers 490 are disposed on both the lateral surfaces of the backrest 400. The walls 480 are located between the flexible sheet 421 and the backrest 400. The rollers 490 hold the both lateral ends of the flexible sheets 421. Both the rollers 490 are configured to wrap the flexible sheet 421, thereby generating the tensional force along the lateral direction of the flexible sheet 421. That is, the rollers 490 act as the tension means.

The controller 240 is configured to control the roller 490 such that the rollers 490 wrap the flexible sheet 421. Consequently, the rollers 490 apply the tensional force along the lateral direction of the flexible sheet 421. Therefore, the rollers 490 move the width center of the flexible sheet to the front direction. As a result, the flexible sheet 421 moves the portion of the user corresponding to the width center of the flexible sheet 421. Consequently, the chair type stretching apparatus gives the stretch to the user.

Next, the modification of the seat 300 is explained. In this modification, detail explanations of configurations of the seat 300 which are equivalent to the configurations of the backrest 400 are omitted.

FIG. 15 shows a seventh modification of the embodiment of the chair type stretching apparatus. In this modification, the seat 300 has a stretching unit 350. The stretching unit 350 has its top surface with the flexible sheet 311. The stretching unit 350 is shaped to have a sack. The air-bag 310 is disposed in the both lateral ends of an inside of the stretching unit 350. The stretching unit 350 is detachably attached to the seat 300.

The stretching unit 350 is made of the cloth. The stretching unit 350 is shaped to have a dimension for covering an entire top surface of the seat 300. The stretching unit 350 is provided at its both lateral ends of the inside with air-bags 310. That is, the air-bags 310 is configured to apply the tensional force along the width direction of the flexible sheet 311. The stretching unit 350 is provided at its front end with a fastener which is not shown in the illustrations. The stretching unit 350 is attached to the seat by the fastener. The stretching unit 350 comprises a hose (not shown) which is communicated with the air-bags 310. The hose has one end which is connected to a connecting port (not shown) disposed on the side of the backrest 400. Consequently, the air-bags 310 are communicated with the pump 220.

Therefore, it is possible to apply tensional force along the lateral direction to the stretching unit 350 when the stretching unit 350 is disposed on the seat 300 and the air-bags 310 are expanded. Consequently, it is possible to obtain the chair type stretching apparatus being configured to give the stretch to the user's buttocks. Furthermore, it is possible to employ the seat 300 having a plurality of the fasteners which extend along the lateral direction and is arranged along the front-back-direction. In this case, it is possible to vary the position of the stretching unit 350 on the seat 300. In addition, it is also possible to detach the stretching unit 350 from the seat 300.

FIG. 16 shows an eighth modification of the embodiment of the chair type stretching apparatus. In this modification, the flexible sheet 311 has both lateral end of the inside surface with hook tapes which is not shown. On the other hand, the seat 300 is provided at its predetermined areas of the both lateral surface with the loop tapes 312. The flexible sheet 311 is attached to the seat 300 by means of the engagement of the loop tapes 312 to the hook tapes.

Therefore, it is possible to apply tension to the flexible sheet 311 according to the expansion of the air-bags 310 when the flexible sheet 311 is attached to the seat 300. Consequently, the flexible sheet 311 is capable of giving the stretch to the user. In addition, the hook tapes are capable of being engaged with predetermined areas of the loop tapes in the vertical direction. Therefore, it is possible to vary an amount of the slack of the flexible sheet 311 in the lateral direction when the engagement position of the loop tape to the hook tape in the vertical direction is varied. In addition, it is also possible to vary the position of the flexible sheet by varying the engagement position of the loop tape to the hook tape in the front-back direction. As a result, it is possible for the flexible sheet to give the stretch to variety portions of the user.

In addition, it is also preferred that the flexible sheet 311 has only one lateral end which is detachably attached to the seat 300. This configuration also makes it possible to vary the engagement position in the vertical direction of the hook tape with respect to the loop tape 312. Consequently, it is possible to obtain the chair type stretching apparatus being capable of adjusting an intensity of the stretch given to the user.

FIG. 17 shows a ninth modification of the embodiment of the chair type stretching apparatus. In this modification, the seat 300 is provided with one the air-bag 310 instead of two the air-bags 310. The chair type stretching apparatus in this modification is configured to give the same stretch the user.

In particular, the seat 300 is provided at its one lateral end with a wall 380. the wall extends toward an upper direction from the seat 300 and the other lateral end with an air-bag 310. In this modification, the wall 380 is located at the left end of the top surface of the seat 300, and the air-bag 310 is located at the right end of the top surface of the seat. The flexible sheet has one lateral ends (left end) which is fixed to a tip of the wall 380, and the other lateral end (right end) which is fixed to the side surface of the seat 300. Consequently, the air-bag 310 is located between the flexible sheet 311 and the seat 300.

FIG. 17 (b) shows the air-bag 310 which expands toward the upper direction. As seen in FIG. 17 (b), the air-bag 310 applies the tensional force along the lateral direction of the flexible sheet 311. The tensional force moves a portion of the user's body toward an upper direction. Therefore, the chair type stretching apparatus gives the stretch to the user. It is noted that the air-bag 310 is shaped to expand to have a dimension along the vertical direction. The dimension along the vertical direction of the air-bag 310 is approximately equal to a dimension along the vertical direction of the wall 380.

FIG. 18 shows a tenth modification of the embodiment of the chair type stretching apparatus. In this modification, the chair type stretching apparatus in this modification has the flexible sheet 311, the walls 380, and rollers 390. The walls 380 have top surfaces extending from the top surface toward the upper direction. The rollers 390 are configured to wrap the flexible sheet 311 over the side surface of the walls 380.

The rollers 390 are disposed on both lateral ends of the seat 300. When the rollers 390 wrap the flexible sheet 311, the rollers 390 applies the tensional force along the lateral direction. Consequently, the rollers 390 move the width center of the flexible sheet toward the upper direction. That is, the rollers 390 act as the tension means. In addition, when the rollers 390 is wound off, the flexible sheet 311 is capable of having the slack.

Therefore, as shown in FIG. 18 (b), when the rollers 390 are operated in order to apply tensional force to the flexible sheet 311, the flexible sheet with tensional force moves the user's buttocks toward the upper direction. Therefore, this configuration makes it possible to give the stretch to the user.

Next, a modification of the backrest with using the air-bag 420 is explained. The following explanation is realized by means of the air-bag 420 on the backrest 400. However, the invention is capable of being applied to the air-bag 310 on the seat 300. It is noted that configurations which is equivalent to the configurations already mentioned above are omitted. Therefore, particular configurations is only explained in following explanation.

As shown in FIG. 19 (a), the backrest 400 is provided with the air-bag 420 and a plate 500. The air-bag 420 shaped to have a bellows is fixed on the front surface of the backrest 400. The plate 500 is fixed on the front end of the air-bag 420. The plate 500 is hard. A front surface of the plate 500 holds the flexible sheet 421. Furthermore, the plate 500 has both vertical ends which are respectively rotatably fixed to one end of the support members 510, 520. The backrest 400 rotatably supports the lower end of the support member 520. The backrest 400 is provided at its front surface with the slide member 540. The slide member rotatably supports the upper end of the support member 510, and also slidably supports the upper end of the support member 510.

When the air-bag 420 receives the air from the pump, the slide member 540 slides the upper end of the support member 510 toward a lower direction. According to movement of the upper end of the support member 510, the upper end of the support member 510 rotates such that the support member 510 allows the plate 510 to move toward the front direction. As a result, the plate 510 applies the tensional force along the width direction to the flexible sheet 421. Therefore, the user applies the force to the air-bag 420 and the plate 500. The support members 510 and 520 gradually stand with respect to the front surface. As a result, a large ratio of the force applied from the user to the air-bag 420 and the plate 500 is supported by the support members 510 and 520. That is, a ratio of the force applied from the user to the air-bag 420 is reduced. Thus, this configuration makes it possible to move the user toward the front direction with low force.

In the eleventh modification in FIG. 19 (b), one end of the plate shaped support member 530 is rotatably supported to the front surface of the backrest 400, and the other end of the plate shaped support member 530 supports the flexible sheet 421. The air-bags 420 with bellows are disposed on the front surface of the backrest 400. The air-bag 420 has the front surface which is fixed to the rear surface of the support member 530.

When the air-bag 420 receives the air from the pump 220, the air-bag 420 is expanded. According of expansion of the air-bag 420, the one end of the support member 530 is moved toward the front direction, while the other end of the support member 530 is rotated. In this case, the air-bag 420 moves the flexible sheet by the force generated by the principle of leverage and large stroke. Therefore, the air-bag 420 is capable of applying the tensional force to the flexible sheet.

Although the present invention is described with particular reference to the above illustrated embodiment and modifications, the present invention should not be limited thereto, and should be interpreted to encompass any combinations of the individual features of the embodiment and modifications. 

1. A chair type stretching apparatus having a seat and a backrest which respectively have individual widths along a width of a user's body, said stretching apparatus comprising: a flexible sheet being disposed in front of said backrest to extend an entire width of said backrest for supporting the user's body, said flexible sheet being configured to be movable between a normal position and a projected position, said flexible sheet in said normal position lying in a close relation with a front surface of said backrest, said flexible sheet in said projected position being spaced away from said front surface of said backrest; a tension means being provided on said backrest and being configured to apply tensional force to said flexible sheet so as to move a center of said flexible sheet toward a front direction of the backrest; a controller being configured to control said tension means in order to move said center of said flexible sheet to a front-back direction, wherein said tension means is provided on at least one width end of the backrest in order to apply the tensional force along a width direction of the backrest to said flexible sheet, whereby the tension means moves said center of said flexible sheet to the front-back direction.
 2. The stretching apparatus as set forth in claim 1, wherein said tension means is defined by a pressurizing means being configured to apply force along the front direction of the backrest to said flexible sheet, said pressurizing means being located between the backrest and said flexible sheet, thereby moving said center of said flexible sheet toward the front direction, said controller being configured to control said pressurizing means so as to move said center of said flexible sheet along the front-back direction of the backrest, said pressurizing means is disposed to both width ends of the backrest in order to apply the force toward a front direction of the backrest to said flexible sheet, whereby said pressurizing means moving said center of said flexible sheet toward a front direction of the backrest.
 3. The stretching apparatus as set forth in claim 2, wherein said pressurizing means is composed of air-bags and a pump, said air-bags being configured to expand and contract along the front-back direction, and said pump being configured to send air to said air-bags.
 4. The stretching apparatus as set forth in claim 2, wherein said flexible sheet and said pressurizing means are detachably attached to said backrest.
 5. The stretching apparatus as set forth in claim 4 further comprising a stretching unit which detachably attached to said front surface of said backrest, said stretching unit being provided at its front surface with said flexible sheet, and being provided at its width ends of an inside of the stretching unit with said pressurizing means so that said flexible sheet and said pressurizing means are detachably attached to said backrest.
 6. The stretching apparatus as set forth in claim 2, wherein said flexible sheet has width ends which are respectively attached to both width surfaces of said backrest, and at least one of said width ends of said flexible sheet being detachably attached to a predetermined area of said width surface of said backrest.
 7. The stretching apparatus as set forth in claim 1 further comprises a wall, said wall being located between said backrest and said flexible sheet, and being located at one width end of the front surface of the backrest, the tension means being defined by a pressurizing means being configured to apply force along the front direction of said backrest to said flexible sheet, said tension means being located between said backrest and said flexible sheet so as to move said center of said flexible sheet, said controller being configured to control said pressurizing means in order to move said center of said flexible sheet toward the front-back direction, said pressurizing means being located at one width end of said backrest and being located away from said wall, said pressurizing means being configured to apply the force along the front direction of said backrest to one end of said flexible sheet so that said pressurizing means applies the tensional force directed outwardly of the width direction to said flexible sheet.
 8. The stretching apparatus as set forth in claim 1 further comprises walls, said walls being provided on the front surface of the backrest and being located at both width ends of said front surface of said backrest, said tension means is defined by rollers said rollers respectively holding said width ends of said flexible sheet, and are configured to wrap said flexible sheet around said rollers so as to move said center of said flexible sheet toward said front direction of said backrest, said controller being configured to control said rollers in order to move said center of said flexible sheet to the front-back direction, said rollers being disposed at both width surfaces of said backrest for wrapping said flexible sheet so that said rollers apply the tensional force directed outwardly of the width direction to said flexible sheet.
 9. The stretching apparatus as set forth in claim 2, wherein said backrest is formed at its center of said front surface with an opening, and having an applicator being disposed within said backrest and is configured to move toward a front direction from said opening to apply force along the front direction, said flexible sheet being shaped to cover said opening.
 10. The stretching apparatus as set forth in claim 9, wherein said flexible sheet is composed of a front cover and a rear cover, said front cover being located in front of said rear cover, said rear cover lying in a close relation with the front surface of the backrest, and said rear cover having an extension ratio or an amount of slack along the width direction, the extension ratio or an amount of the slack of said rear cover being smaller than the extension ratio or an amount of the slack of said front cover.
 11. The stretching apparatus as set forth in claim 9, wherein said flexible sheet having an extension ratio along a height direction of said backrest, and an extension ratio along the width direction of said backrest, and the extension ratio along the width direction being smaller than the extension ratio along the height direction.
 12. The stretching apparatus as set forth in claim 9, wherein said flexible sheet has an amount of slack along a height direction of the backrest, and an amount of slack along the width direction, and an amount of the slack along the width direction being smaller than an amount of the slack along the height direction.
 13. The stretching apparatus as set forth in claim 9, wherein said flexible sheet has a first area for receiving the tensional force along the width direction from said pressurizing means, and a second area for receiving the force along the front direction from said applicator, said first area has an extension ratio or an amount of slack, said second area has an extension ratio or an amount of slack, the extension ratio or an amount of the slack of the first area is smaller than the extension ratio or an amount of the slack of the second area.
 14. The stretching apparatus as set forth in claim 3, wherein said flexible sheet and said pressurizing means are detachably attached to said backrest.
 15. The stretching apparatus as set forth in claim 14 further comprising a stretching unit which detachably attached to said front surface of said backrest, said stretching unit being provided at its front surface with said flexible sheet, and being provided at its width ends of an inside of the stretching unit with said pressurizing means so that said flexible sheet and said pressurizing means are detachably attached to said backrest. 